In mid-October 2011, NASA scientists working in Antarctica discovered a massive crack across the Pine Island Glacier, a major ice stream that drains the West Antarctic Ice Sheet. Extending for 19 miles (30 kilometers), the crack was 260 feet (80 meters) wide and 195 feet (60 meters) deep. Eventually, the crack will extend all the way across the glacier, and calve a giant iceberg that will cover about 350 square miles (900 square kilometers).

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA’s Terra spacecraft acquired this image on November 13, 2011. The glacier is textured, rough compared to the surrounding West Antarctic ice sheet. The Pine Island Glacier moves quickly, draining 100 meters of ice per year. The calving event shown here is natural. The last major calving event occurred in late 2000 and 2001 and was also imaged by ASTER.